Modification of the electrically driven percussion drill



Get. 8, 1935. DEDERER Zfilfifi MODIFICATION OF THE ELECTRICALLY DRIVEN PERCUSSION DRILL Filed May 22, 1935 Patented Oct. 8, 1935 UNITED STATES MODIFICATION OF THE ELECTRICALLY DRIVEN PERCUSSION DRILL Richard Dederer, Stuttgart, Germany, assignor to the firm Kapital & Industriewerte A. G., Basel,

Switzerland Application May 22, 1935, Serial No. 22,884 In Germany November 6, 1934 7 Claims.

The present invention relates to an improve ment in or modification of the electrically driven percussion drill according to Patent No. 1,984,256 and has as its object an electrically driven combined percussion and drilling device.

The percussion and drilling device according to this invention comprises, in addition to the means for producing impacts on the ram carrying the tool which enables a clean blow to be 10 efiected, also means for effecting positive rotation of the tool during the percussion action, whereby a drilling impact is rendered possible, and a device for cutting out the impact-producing action, whereby the device can be used for pure drilling purposes. Further means may be provided which enable drilling to be effected at two dilferent speeds.

The accompanying drawing diagrammatically illustrates an embodiment of the percussion and drilling device of this invention. The figure is a longitudinal section through the driving and change over mechanism of the device.

Referring to the drawing, it represents the hammer'casing in which the electrically driven main shaft b is disposed. The shaft 1) is provided with a stationary pinion c and a vertically displaceable pinion d. The pinion c is in permanent engagement with the toothed rim of the drill socket e, whilst the pinion 11, provided with coupling studs is in vertically displaceable engagement with the. toothed rim of the operating cam g. With the aid of the change over lever h the pinion 11 can be coupled with the pinion 0 when the former is moved in the direction of the arrow h. The operating cam g is then also rotated in known manner and the percussion instrument is in operation.

In the position illustrated in the drawing the percussion device is disconnected and the drill socket e rotates positively between the two ball thrust bearings, whilst the operating cam is held fast by the percussion elements pressing thereon. The drill socket e is provided with longitudinal grooves i, which are adapted to receive the tool. A cone is serving for the reception of a drill chuck is disposed on the continuation of the driving shaft b.

The operating cam g possesses a concentric projection n, which is rotatably mounted in a bore of the socket e. The ram Z is rotatably mounted in the projection n, and its extension 0, which is provided with a bore m for the reception of the tool, moves in the axial bore of the socket e.

- The head p of the device is bored axially for the reception of the socket e, the widened rim q of the of being used for several purposes by changing socket e, which carries a toothed rim, is disposed on balls on the upper surface of the head of the device, and the rim q serves as a track for the rim 1" of the operating cam carrying the toothed rim. The operating cam g with projection n, the ram Z with projection o and bore m, the socket e with bore, the head t with bore, the marginal discs 1 and q together with their toothed rims as well as the grooves i of the socket e are all disposed coaxially to one another and exactly centered.

If the device is to be utilized only for pure percussion operations, a tool, which does not engage in the grooves 13, is inserted in the bore m, and the lever h is moved over in the direction of the arrow it, so that the studs 1 of the pinion engage in and couple up with the recesses in the pinion 0 and the operating cam g is positively rotated. If it is desired to employ the device alternately as a boring or drilling tool and as a percussion drill, a tool which is provided on its enlarged periphery with ribs which fit in the grooves i of the socket e, is inserted in the bore m. By uncoupling the pinion d the device may be made to carry out only drilling operations and by coupling in the pinion d the instrument may be made to carry out percussion-drilling operations. Since the shaft 1) rotates at a different speed to the bore socket eit is possible by using the shaft 1) as drill-driving shaft to drill at different speed than with the aid of the socket e.

The device according to the invention, owing to its peculiar form of construction, can find very general application. Owing to the progressive development in the field of high-grade tool steels, it is today possible successfully to employ rotating drills with refined steel welded thereon for breaking through masonry. In such cases the efficiency of an exclusive percussion drill is 40.

left far behind when soft rocks or stones are to be breached.

On the other hand it is possible, when necessary in the case of altered local conditions, to pass over to combined drilling and percussion or pure percussion, without having to insert another tool; or alternatively higher drilling speeds may be employed by using the shaft 1) as a drilling shaft.

The object aimed at of providing a tool capable over may, for example, be attained by arranging the pinion that drives the operating cam to be axially displaceable and not rotatable on the main driving shaft and rotatably mounting the pinion that drives the drilling socket, the change over device being with advantage so constructed that the first mentioned pinion can be fixed in the driving position for the operating cam Without at the same time being coupled with the second pinion. If the first pinion is in driving connection with the operating cam, the device functions as a pure percussion instrument, whilst if the pinion is simultaneously coupled with the sec ond pinion, the device functions as a percussiondrilling instrument, when the tool in question engages in the grooves i. A third pinion position may also be provided whereby the first pinion does not drive the operating cam, but is only coupled with the second pinion. In this position the device functions as a pure drilling tool, if a tool is selected which engages in the grooves i.

The construction of electrically driven percussion devices according to the invention has particular advantages in such devices in which the percussion elements are constructed with a crosssection in the form of a sector of a circle and form together a cylinder of circular cross-section and in which the percussion elements rest on the operating cam and are lifted by the lugs on the operating cam and then fall on the ram.

What I claim is:

1. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an extension of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable of being coupled together, the pinion driving the operating cam being axially displaceable and rotatably mounted on the shaft, the pinion driving the drill socket being fixed on the shaft, and means for bringing the first-mentioned pinion into and out of engagement with the second pinion.

2. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an extension of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable of being coupled together, the pinion driving the operating cam being axially displaceable but not rotatable on the shaft, the pinion driving the drill socket being disposed free on the shaft, and changing over means adapted to bring the first mentioned pinion into and out of engagement with the second pinion.

3. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an exten sion of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a

ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable 5 of being coupled together, the pinion driving the operating cam being axially displaceable on the shaft, and a device for fixing the pinion in any desired position on the shaft.

4. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an extension of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable of being coupled together, the main driving shaft passing through the closing head, and an extension of the shaft outside of the head adapted to receive the drill chuck.

5. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a, main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an extension of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable of being coupled together, in the drill socket, in addition to the bore for the operating cam extension and the ram, an externally open bore for the reception of the two, and grooves in the wall of the bore adapted to receive the tool on rotation of the drill socket.

6. In an electrically driven percussion device, means for raising percussion elements and allowing the same to fall, a casing enclosing the said means, a bored closing head on the casing, a main driving shaft in the casing, a drill socket concentrically and rotatably disposed in a bore of the casing head, an operating cam, an extension of the operating cam concentrically and rotatably disposed in a bore of the drill socket, a ram and a return spring concentrically mounted in a bore of the operating cam extension and in a bore of the socket, a bore in the ram for the recepti-on of the tool, at least two pinions mounted so on the main shaft, the pinions being capable of being coupled together, a marginal extension of the operating cam, a toothed rim on this mar ginal extension adapted to engage with one pinion, a marginal extension of the drill socket, a toothed rim on the latter marginal extension adapted to engage with the other pinion, the marginal extension of the operating cam being mounted with ball bearings on the marginal extension of the drill socket, the marginal extension of the drill socket being mounted with the aid of ball bearings on the inner surfaces of the head of the casing.

7. In an electrically driven percussion device, means for raising percussion elements and allow- 76 reception of the tool, at least two pinions mounted on the main shaft, the pinions being capable of being coupled together, the percussion elements constructed with a cross section in the form of a sector of a circle, forming together a cylinder of circular cross section, the said percussion elements resting on the operating cam adapted to be lifted by lugs on the cam and falling on the ram.

RICHARD DEDERER. 

